The adult organisation of Paragordius varius. 425 
cloacal ganglion divides into two, in accordance with the bifurcation 
of the caudal nerves in this region. In the transverse plane where 
the cloacal aperture is found (Fig. 86, Pl. 43) the neural lamella of 
each nerve (Cd. N) is attached to the hypodermis (Hyp) at the point 
where it passes into the cloacal epithelium (Cl. Epi), a few chromo- 
philic fibres were seen to enter the cloacal wall; probably chromo- 
phobic fibres enter also, but they could not be demonstrated; thus in 
the male the region of the innervation of the cloaca is different from 
the female. 
K. Function of the different Cells of the Nervous 
System. 
We have seen that two elements occur within the central nervous 
system, the chromophilic and the chromophobic. The former send 
their fibres into the hypodermis, where they terminate generally as 
plexuses; such fibres penetrate for only a short distance into the 
cloacal nerves, and in no case could any connection of them be seen 
with other than hypodermal elements. The cloacal nerves of the 
female and the genital nerves of the male could be demonstrated to 
be constituted almost entirely of chromophobic nerve fibres; hence 
such nerve fibres probably innervate both the cloaca and the genital 
organs, and may be considered visceral nerve fibres in contradiction 
to the preceding hypodermal fibres. The innervation of the muscu- 
ature could not be determined by o bservation. But it is probable 
that they are not innervated by chromophilic nerve fibres, since if 
such were the case these deep-staining fibres, which appear so sharply 
marked upon all suitably stained preparations, would certainly show 
anatomical connections with the muscle cells. Therefore, by the ar- 
gument of exclusion, we might conclude that the chromophobic nerve 
cells innervate the musculature also, so that some of them would be 
motor in function. Motor nerve cells are generally larger than sensory 
ones, and this accords with the difference in size of the chromophilic 
and chromophobic nerve cell bodies. We have also seen that there 
are two types of the chromophilic cells, the small type and the large 
type (giant cells); one kind of these might innervate the musculature, 
the other the ‘cloaca and genital organs. 
L. The general Structure of the Nervous System. 
From the preceding description it will be seen that there is no 
evidence of metamerism or segmentation in the nervous system. The 
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